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Description of Business, Basis of Presentation and Significant Accounting Policies - Activities Relating to Capitalized Software (Detail) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Movement in Capitalized Computer Software, Net [Roll Forward] |  |  |
Amortization | $ (23) | $ (33) | $ (49)
Internal-Use Software |  |  |
Movement in Capitalized Computer Software, Net [Roll Forward] |  |  |
Beginning balance at January 1 | 13 | 15 | 16
Capitalized | 7 | 5 | 6
Amortization | (7) | (7) | (7)
Ending balance at December 31 | 13 | 13 | 15
External-Use Software |  |  |
Movement in Capitalized Computer Software, Net [Roll Forward] |  |  |
Beginning balance at January 1 | 23 | 57 | 105
Capitalized | 0 | 0 | 0
Amortization | (23) | (34) | (48)
Ending balance at December 31 | $ 0 | $ 23 | $ 57

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- Definition Additions made to capitalized computer software costs during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275 + Details
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- Definition Amount of expense for amortization of capitalized computer software costs. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 985 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 985 -SubTopic 20 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128487-111756 + Details
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- Definition The carrying amount of capitalized computer software costs net of accumulated amortization as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 985 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756 + Details
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
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- Details
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